Machine tool



Patented Aug. '11, 1970 Sheet Fig.

Patented Aug; 11, 1970 Z- of 5 Sheet 71a Wl/ W illllllllililp United States Patent [72] inventor Marcel L. Neuman Collonges-au-Mont DOr, France 211 App]. N0. 688,156

[22] Filed Dec. 5, 1967 [45] Patented Aug. 11,1970

[73] Assignee Societe Anonyme des Anciens Etablissements Charles Berthiez, Paris, France a French Society [32] Priority Dec. 20, 1966 [3 3 1 France [54] MACHINE TOOL 8 Claims, 6 Drawing Figs.

[52] US. Cl 90/11, 52/223 [51] Int. Cl B23c 1/00,

[50] Field ofSearch 90/11, l4, 15, 16; 77/3.l, 3; 52/296, 223, 227

[56] References Cited UNITED STATES PATENTS 795,362 7/1905 Numan 52/223 1,026,801 5/1912 116656.... 52/227x 3,154,006 10/1964 Novak 52/223x 3,264,905 8/1966 Erikson 90/16x I FOREIGN PATENTS 607,681 9/1960 ltaly 52/223 lPrimary Examinen- Gil Weidenfeld Attorney-Liddy, Sullivan and Hart ABSTRACT: A machine tool wherein the vertical tool carrying column of the machine tool is secured to the supporting bed by tensioned rods whereby the vertical column and bed are held together rigidly in compression.

MACHINE TOOL This invention relates to a cutting, milling, boring or like machine tool of the kind comprising a bed, a table mounted on said bed for supporting a work piece, a vertical column mounted on said bed and having a tool carrying assembly vertically slidable thereon, said assembly including a horizontally slidable carriage carrying a cutting, milling, boring or like tool. The main problem which arises in the construction of such machine tools is to provide the vertical column with sufficient stability to support the weight of the tool carrying assembly and withstand the forces to which it is subjected under operating conditions. lf the conditions are such that the resultant of the forces in the region of the junction of the vertical column on the bed lie within the middle third of the base of the column no tensile stresses arise and the 'whole unit behaves like a monolithic structure. These conditions however, obtain very exceptionally and the resultant forces usually pass through the outside of the base, in which case the junction between the base of the column and the bed, tends to open or parts of the flange by which the column is bolted to the bed tend to bend and thus considerably reduce rigidity and'stabili- The object of the present invention is to overcome this problem and to provide a construction in which all parts at the junction of the vertical column and the bed are as far as possible subjected only to compression under all operating conditions and thus eliminate or reduce loss of rigidity and stability of the vertical column which occurs in known constructions.

With this object in view the present invention consists of a machine tool of the kind described wherein the vertical column supportingthe tool carrying assembly is mounted on the machine bed by means of one or more tie rods under tension, the arrangement being such that said tensioned tie rod or each of said tie rods hold said vertical column in rigid bearing relationship with said bed in such a manner that said column and said bed are prestressed in compression.

According to another aspect of the invention the vertical column is mounted on the machine bed by a plurality of tie rods each of which is attached at one of its ends to said column and at its other end to said bed, said tie rods being pretensioned so as to hold said column on said bed under compres- In order that the invention may be more clearly understood one particular embodiment thereof will now be described by way of example, with reference to the accompanying drawings in which FIGURE 1 illustrates diagrammatically in side elevation at type of machine tool to which the present invention relates.

FIGURE 2 is a sectional view on the line ll-ll of FIGURE 1 and showing the bed of the machine in plan and the work table and tool carrying assembly in broken lines,

FIGURE 3 is a sectional view on an enlarged scale taken on the line lll-lll of FIGURE 2.

FIGURE? is a view similar to FIGURE 3 showing a modification in which tie rods are also utilised for clamping the bed of the machine to a concrete foundation or base.

FIGURE 5 is an axial section on a still larger scale illustrating means for tensioning the tie rods, and

FIGURE 6 is a section on the line Vl-Vl of FIGURE 5. Referring to these drawings a machine tool of the kind to which the present invention relates is shown in FIGURE 1 and comprises a bed 4, upon which is mounted a support table 6, for supporting a work piece and a vertical column 1 on which is slidably mounted a tool carrying assembly including a horizontal member 2 upon which is horizontally slidable a car-,

riage 3 for mounting a suitable cutting, milling, boring or other tool. a

The vertical column I is rigidly fixed to the plane surface 5 of the bed 4 by a plurality of tie rods 7 as illustrated in FIGURES 2 and 3. In the embodiment shown seven tie rods 7" to 7 pass through vertical channels or passages 7a form-ed I within substantially U-shaped ribs 7b on the inside of the verti cal column and integral with the wall thereof, said tie rods vertical column 1 and bed 4 are prestressed in compression through their vertical height and the base of the vertical column is pressed tightly against the plane surface 5 of the bed 4.

In a modification shown in FIGURE 4 each of the tie rods pass through a concrete or other foundationlO upon which the bed 4 is supported. In this embodiment a pressure plate 11 and a part spherical washer 12 are positioned between the nut 9, screwed on to the lower end of the tie rod, and the under surface of the foundation 10, and a wedging member is provided between the base of the vertical column 1 and the upper surface of the concrete foundation 10.

The wedging member comprises two co-operating wedge elements 13 and 14 and an adjusting screw 15 which passes through a hole in a flange at the thin edge of wedge element 13 and screws into a tapped hole in the thick end of wedge 14 whereby rotation of said screw 15 causes relative movement between said wedge element to effect wedging action between the bed 1 and foundation 10. Both wedge elements l3, 14 are provided with openings for the passage of the tie rod 7. As will be understood in this embodiment not only the bed 4 and column 1 but also the foundation 10 is prestressed in compression by the tie rods.

In either of the embodiments shown in FIGURES 3 and 4 the length of the tie rods can be reduced by interposing a rigid transmission or support member (not shown) between for example the upper end of the vertical column and the upper ends of the tie rods, or between the lower ends of the tie rods I and the bed, or between both ends of the tie rods and the column and bed respectively, these members being arranged so as to transmit the compressive force of the tie rods to the column and/or bed. Alternatively one suchmember may be provided for each rod.

In order to ensure that the column is always perfectly mounted on the bed 4 over the whole of the area of the plane of the surface 5, it is necessary for the prestressing in compression of this plane surface of the joint to be higher than the' greatest tensile stress which could occur in the column bed assembly if the bed and column formed a monolithic structure. This prestressing is calculated or determined by means of extensiometers on a mock-up with a precision sufficient to provide a correct adjustment at the first attempt, providing an effective way can be found of placing the tie rods 7 under controlled tension,

The tensioning of the tie rods can be effected in any suitable manner but a suitable means therefor is illustrated in which said piston can be screwed onto the upper external screw threaded end of the tie rod. The piston 16 is slidable in a cylinder 17 and the'axial cylindrical extension 16a is slidable in an opening in a closed end of said cylinder 17 with suitable sealing rings 18 and 18a between the piston 16 and cylinder 17 and between the cylindrical extension 16a of the piston and the opening in the closed end of the cylinder 17 respectively. The closed end of the cylinder 17 is provided with legs 25 adapted to bear against the upper end of the vertical column 1. The legs 25 are circumferentially spaced'around the closed end of the cylinder 17 so as to surround a nut 8, as shown when said legs bear against the upper end of the column 1.

The nut 8 is provided with a series of circumferentially spaced 7 5 radial holes-8a by means of whic'hsaid nut can be rotated by a tommybar; 24'. a

onto the upper end of the tie rod and tightened by means of the tommy bar 24 until the tie bar is under initial tension. The

cylinder 17 is then placed on the upper end of the column 1 with its legs positioned around the nut 8. The piston 16 is then screwed onto the upper end of the tie rod until its lower sur-' face is closely adjacenfto or in contact with the inner face of the closed end of the cylinder 17. The relief valve 22 is then closed and the pump 20 operated to pump fluid under pressure into the chamber 19. Operation of the pump is continued to cause the pressure fluid to act on the piston .16 until the tie rod, to which the piston is connected, is thereby placed under a predetermined tension. This tensioning of the tie rod will result in the nut 8 being moved away from the upper end of the column 1 and said nut is then again'screwed down into engagement with the column 1 by means of the tommy bar 24.

After the tensioning of the rod in this manner with the resulting prestressing in compression of the column 1 and bed 4, the relief valve is opened to release the fluid pressure on the piston 16 after which the complete hydraulic device 16, 17 is removed from the tie rod.

Although the invention has been described as applied to a machine tool having a single vertical support column it will be understood that it can of course also be applied to machine tools having more than one vertical column.

It must also be understood that the invention is not limited to other details of construction of the particular embodiment described but may be modified in various ways without departing from the scope of the invention. For example, the vertical column 1 may be connected with a greater or lesser number of the rods than are used in 'the embodiment described and means other than the hydraulic means shown in FIGURES and 6 may also be used for tensioning the tie rods.

I claim:

1. A machine tool comprising a bed, a table mounted on said bed for supporting a work piece to be machined, a unitary vertical column having its bottom surface seated on said bed adjacently to said table, a tool carrying assembly mounted on said vertical column for working on a piece supported on said table, and vertically disposed means for rigidly securing said column and bed together and for subjecting said vertical column and all supporting surface portions of the vertical column and bed at the juncture thereof prestressed in compression, said means comprising a plurality of prestressed tie rods being fastened along at least three locations near the perimenter of the cross-sectionalarea of said column to effect compressive stresses on said vertical column and at all of said supporting juncture surface portions of the column and bed, means connecting an upper portion of each prestressed tie rod to the upper portion of said column, and means connecting a lower portion of each prestressed tie rod to said bed, said tie rods each being prestressed to a precise predetermined tension effected by means capable of applying thereto a measured controlled force such as to subject the vertical column and the associated supporting juncture surface portion to compressive forces greater than the greatest tensile stress which could occur in the column-bed assembly if integrally formed, said connecting means being selectively adjusted to maintain such given force on an associated rod while such force is being applied thereto, and said prestressed tie rods being in such number and arrangment that said vertical column and all of said supporting juncture surface portions are subjected to said compressive forces.

2. A machine tool according to Claim 1 wherein said tie rods are each attached at one of its ends to said vertical column and at its other end to said bed. I

3. A machinetool according to Claim 1, wherein said tie rods pass thr'oughchannels in said vertical column and said bed and exert pressure on the bottom ends of the channels at the under sides of s'aidcolumn and on the opposing upper ends of the channels at the upper side of said bed. I

4. A machine tool according to Claim 3 wherein said means connecting the upper portions of each tie rod to said column is seated on the upper end of the associated channel in said vertical column and transmits the pressure of the tie rod thereto, and said means connecting a lower portion of each tie rod to said bed is seated on the lower end of the associated channel in said bed and transmits the pressure of the tie rod thereto-- 5. A machine tool according to Claim 1, wherein said bed is mounted on a foundation and each of said tie rods passes through said vertical column, said bed and said foundation and is connected at one of its ends to the upper end of said vertical column and at its other end to the underside of said foundation to thereby hold said vertical column, bed and foundation under prestressed compression.

6. A machine tool according to Claim 5, wherein a wedge assembly is positioned between said foundation and said bed.

7. A machine tool according to Claim 1 and comprising hydraulic means for tensioning said tie rod, said hydraulic means comprising a hydraulic cylinder adapted to be supported on said vertical column, a piston slidable in said cylinder and adaptedto be removably connected with said tie rod and a pump for supplying pressure fluid to the chamber of said cylinder through an hydraulic circuit containing a manometer and a relief valve.

8. A machine tool according to Claim 4, in which said unitary vertical column is hollow throughout the length of the portions of the tie rods extending through such column, and said tie rods are circumferentially arranged in spaced relation around the exterior wall of said hollow column. 

